Evaluation of stability limits of wheelchair rugby athletes and their relationship with functional classification and competitive level

Abstract

Introduction: Wheelchair Rugby is a Paralympic modality created for individuals with tetraplegia or tetra-equivalent disabilities. Usually, WR athletes show a partial or total loss of trunk function, affecting the seated postural stability. Being an important factor of the classification process of WR athletes, it is important to determine how the score of functional classification and the competitive level influence trunk function. Objective: We aimed to evaluate the influence of sport-specific classification and competitive level on the seated limits of stability (LS) of wheelchair rugby players. Methods: Twenty-eight subjects were recruited from international and national level WR teams. Athletes were distributed into three groups according to their classification: low-point group (0.5 to 1.5-point); mid-point group (2.0-2.5-point) and high-point group (3.0-3.5-point). Participants were asked to seat on a force platform placed upon a wooden block and to lean the body as far as possible in eight directions indicated on a computer screen. Center of pressure (COP) coordinates were calculated from the ground reaction forces acquired with the force platform. Seated limits of stability were computed as the area of 68% confidence elipse adjusted to maximal COP excursion achieved for the eight directions. Results: There was no difference in the limits of stability was observed between international and national level athletes (P=0.722). However, limits of stability were approximately 2 times greater in players from high-point group than from low-point group (P=0.030). Mid-point group was not different from high- or low-point groups (P>0.149). Conclusion: Limits of stability are influenced by sport classification but not by competitive level. Our results highlight the utility of limits of stability as a training-resistant, valid measure of a specific impairment, potentially contributing for the development of an evidence-based wheelchair rugby classification.